Comparison of X chromosome inactivation patterns among members of MZ twins pairs
In (A), twins 109A and 109B show similar patterns of X inactivation around 50:50. In (B), twin 186A exhibits skewing toward inactivation of the X chromosome bearing the upper AR allele. Her co-twin 186B does not have preferential skewing toward either X chromosome. In (C), both twins 490A and 490B are extremely skewed toward inactivation of the X chromosome bearing the smaller (lower band) AR allele. M = mock-digested DNA; H = HpaII-digested DNA. All assays were performed in duplicate, as shown.